Hollow Co3O4 Nanosphere Surrounded by N-Doped Graphitic Carbon Filled within Multilayer-Sandwiched Graphene Network: A High-Performance Anode for Lithium Storage.

Abstract

We prepared a multilayer-sandwiched Co3O4/NGC/rGO composite by introducing in situ electrostatic self-assembly method with a subsequent thermal annealing induced Kirkendall effect. In the composite, the hollow Co3O4 nanospheres surrounded by N-doped graphitic carbon (NGC) layer are tightly sandwiched between the reduced graphene oxide (rGO) layers. The layer-by-layer multilayer-sandwiched structure and strong electrostatic interaction bring the space confinement effect and close electrical contact between different components, which greatly strengthen the durability of the electrode structure and electron/ion transport kinetics. Detailed characterization based on electrochemical impedance spectra (EIS) and cyclic voltammograms (CVs) tests confirms that the Co3O4/NGC/rGO electrode possesses accelerated electron/ion-transfer kinetics and enhanced surface-controlled capacitive behaviors. The discharging profile and its differential capacity curve further validate the existence of interfacial storage lithium in the composite, contributing to high reversible capacity. Consequently, benefiting from the synergistic effects of the multilevel controls in component and structure aspects, the Co3O4/NGC/rGO composite displays a superior reversible capacity (930.8 mA h g-1 at 0.5 A g-1), desired rate performance (584 mA h g-1 at 10 A g-1), as well as stable cycling lifetime of over 300 loops with almost no capacity fading even without any additional conductive additives.